Photovoltaic module architecture

ABSTRACT

Photovoltaic modules, as well as related systems, methods and components are disclosed. In some embodiments, a photovoltaic module can include a first photovoltaic cell including an electrode, a second photovoltaic cell including an electrode, and an interconnect. The electrode of the first photovoltaic cell can overlap the electrode of the second photovoltaic cell. The interconnect can electrically connect the electrode of the first photovoltaic cell and the electrode of the second photovoltaic cell. The interconnect can mechanically couple the first and second photovoltaic cells.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e)(1) to U.S.Provisional Patent Application Ser. No. 60/575,971, filed on Jun. 1,2004, and entitled “Photovoltaic Cells with Conductive Interconnects”;U.S. Provisional Patent Application Ser. No. 60/590,312, filed on Jul.22, 2004, and entitled “Photovoltaic Modules”; U.S. Provisional PatentApplication No. 60/590,313, filed on Jul. 22, 2004, and entitled“Photovoltaic Cells with Conductive Mesh Interconnects”; and U.S.Provisional Patent Application Ser. No. 60/664,115, filed on Mar. 21,2005, and entitled “Photovoltaic Module Architecture”, all of which arehereby incorporated by reference.

TECHNICAL FIELD

This description relates to photovoltaic modules, as well as relatedsystems, methods and components.

BACKGROUND

Photovoltaic cells, sometimes called solar cells, can convert light,such as sunlight, into electrical energy. A typical photovoltaic cellincludes a layer of a photoactive material and a layer of a chargecarrier material disposed between a cathode and an anode. When incidentlight excites the photoactive material, electrons are released. Thereleased electrons are captured in the form of electrical energy withinthe electric circuit created between the cathode and the anode.

In one type of photovoltaic cell, commonly called a dye-sensitized solarcell (DSSC), the photoactive material typically includes a semiconductormaterial, such as titania, and a photosensitizing agent, such as, forexample, a dye. In general, the dye is capable of absorbing photonswithin a wavelength range of operation (e.g., within the solarspectrum).

In another type of photovoltaic cell, commonly referred to as a polymerthin film cell, the photoactive material used generally has twocomponents, an electron acceptor and an electron donor. The electronacceptor can be a p-type polymeric conductor material, such as, forexample poly(phenylene vinylene) or poly(3-hexylthiophene). The electrondonor can be a nanoparticulate material, such as for example, aderivative of fullerene (e.g., 1-(3-methoxycarbonyl)-propyl-1-1-phenyl-(6,6) C₆₁, known as PCBM).

Photovoltaic cells can be electrically connected together in seriesand/or in parallel to create a photovoltaic module. Typically, twophotovoltaic cells are connected in parallel by electrically connectingthe cathode of one cell with the cathode of the other cell, and theanode of one cell with the anode of the other cell. In general, twophotovoltaic cells are connected in series by electrically connectingthe anode of one cell with the cathode of the other cell.

SUMMARY

In one aspect, a module includes a first photovoltaic cell having anelectrode and a second photovoltaic cell having an electrode. The modulefurther includes an interconnect (e.g., an electrically conductiveinterconnect) that is disposed in the electrode of the firstphotovoltaic cell and the electrode of the second photovoltaic cell sothat the electrode of the first photovoltaic cell and the electrode ofthe second photovoltaic cell are connected (e.g., electrically and/ormechanically connected).

In another aspect, a module includes a first photovoltaic cell having anelectrode and a second photovoltaic cell having an electrode. The modulefurther includes an interconnect (e.g., an electrically conductiveinterconnect) that connects (e.g., electrically connects and/ormechanically connects) the electrode of the first photovoltaic cell andthe electrode of the second photovoltaic cell. The photovoltaic cellsare configured so that a portion of the electrode of the firstphotovoltaic cell overlaps a portion of the electrode of the secondphotovoltaic cell.

In a further aspect, a module includes first and second photovoltaiccells. The first photovoltaic cell includes a cathode, an anode and aphotoactive material between the cathode and the anode. The secondphotovoltaic cell includes a cathode, an anode and a photoactivematerial between the cathode and the anode. The module further includesan interconnect (e.g., an electrically conductive interconnect) that isdisposed in the cathode of the first photovoltaic cell and the anode ofthe second photovoltaic cell so that the cathode of the firstphotovoltaic cell and the anode of the second photovoltaic cell areconnected (e.g., electrically and/or mechanically connected).

In an additional aspect, a module includes first and second photovoltaiccells. The first photovoltaic cell includes a cathode, an anode and aphotoactive material between the cathode and the anode. The secondphotovoltaic cell includes a cathode, an anode and a photoactivematerial between the cathode and the anode. The module further includesan interconnect (e.g., an electrically conductive interconnect) that isdisposed in the cathode of the first photovoltaic cell and the cathodeof the second photovoltaic cell so that the cathode of the firstphotovoltaic cell and the cathode of the second photovoltaic cell areconnected (e.g., electrically and/or mechanically connected).

In another aspect, a module includes first and second photovoltaiccells. The first photovoltaic cell includes a cathode, an anode and aphotoactive material between the cathode and the anode. The secondphotovoltaic cell includes a cathode, an anode and a photoactivematerial between the cathode and the anode. The module further includesan interconnect (e.g., an electrically conductive interconnect) that isdisposed in the anode of the first photovoltaic cell and the anode ofthe second photovoltaic cell so that the anode of the first photovoltaiccell and the anode of the second photovoltaic cell are connected (e.g.,electrically and/or mechanically connected).

In a further aspect, a module includes first and second photovoltaiccells. The first photovoltaic cell includes a cathode, an anode and aphotoactive material between the cathode and the anode. The secondphotovoltaic cell includes a cathode, an anode and a photoactivematerial between the cathode and the anode. A portion of the anode ofthe second photovoltaic cell overlaps a portion of the cathode of thefirst photovoltaic cell. The module also includes an interconnect (e.g.,an electrically conductive interconnect) that connects (e.g.,electrically connects and/or mechanically connects) the cathode of thefirst photovoltaic cell and the anode of the second photovoltaic cell.

In an additional aspect, a module includes first and second photovoltaiccells. The first photovoltaic cell includes a cathode, an anode and aphotoactive material between the cathode and the anode. The secondphotovoltaic cell includes a cathode, an anode and a photoactivematerial between the cathode and the anode. A portion of the anode ofthe second photovoltaic cell overlaps a portion of the cathode of thefirst photovoltaic cell. The module also includes an interconnect (e.g.,an electrically conductive interconnect) that connects (e.g.,electrically connects and/or mechanically connects) the cathode of thefirst photovoltaic cell and the cathode of the second photovoltaic cell.

In another aspect, a module includes first and second photovoltaiccells. The first photovoltaic cell includes a cathode, an anode and aphotoactive material between the cathode and the anode. The secondphotovoltaic cell includes a cathode, an anode and a photoactivematerial between the cathode and the anode. A portion of the anode ofthe second photovoltaic cell overlaps a portion of the cathode of thefirst photovoltaic cell. The module also includes an interconnect (e.g.,an electrically conductive interconnect) that connects (e.g.,electrically connects and/or mechanically connects) the anode of thefirst photovoltaic cell and the anode of the second photovoltaic cell.

In a further aspect, a module includes first and photovoltaic cells,where the first and second photovoltaic cells are configured in astep-wise configuration.

In an additional aspect, a method of electrically connectingphotovoltaic cells includes disposing an interconnect (e.g., anelectrically conductive interconnect) in an electrode of a firstphotovoltaic cell and in an electrode of a second photovoltaic cell toconnect (e.g., electrically connect and/or mechanically connect) theelectrode of the first photovoltaic cell and the electrode of the secondphotovoltaic cell.

In one aspect, a module includes first and second photovoltaic cells.The module also includes an interconnect (e.g., an electricallyconductive interconnect) that connects (e.g., electrically connectsand/or mechanically connects) an electrode of the first photovoltaiccell and an electrode of the second photovoltaic cell. The interconnectincludes an adhesive material and a mesh partially disposed in theadhesive material.

In another aspect, a module includes first and second photovoltaiccells. The first and second photovoltaic cells each include a cathode,an anode and a photoactive material between the cathode and the anode.The module also includes an interconnect (e.g., an electricallyconductive interconnect) that electrically connects (e.g., electricallyconnects and/or mechanically connects) an electrode of the firstphotovoltaic cell and an electrode of the second photovoltaic cell. Theelectrically connected electrodes can be cathode/anode, cathode/cathodeor anode/anode. The interconnect includes an adhesive material and amesh partially disposed in the adhesive material.

In one aspect, a module includes a first photovoltaic cell including anelectrode, and a second photovoltaic cell including an electrode havinga bent end connected (e.g., electrically connected) to the electrode ofthe first photovoltaic cell.

In another aspect, a module includes a first photovoltaic cell includingan electrode, and a second photovoltaic cell including an electrode. Theelectrode in the second photovoltaic cell has a shaped (e.g., dimpled)or bent portion that is connected (e.g., electrically connected) to theelectrode of the first photovoltaic cell.

In one aspect, a module includes a first photovoltaic cell including anelectrode, a second photovoltaic cell including an electrode, and anelectrically conductive interconnect. The electrode of the firstphotovoltaic cell overlaps the electrode of the second photovoltaiccell. The interconnect electrically connects the electrode of the firstphotovoltaic cell and the electrode of the second photovoltaic cell. Theinterconnect mechanically couples the first and second photovoltaiccells.

In another aspect, a module includes a first photovoltaic cell includingan electrode, a second photovoltaic cell including an electrode, thesecond photovoltaic cell overlapping the first photovoltaic cell todefine an overlapping region, and an interconnect adjacent theoverlapping region to electrically and mechanically connect the firstand second photovoltaic cells.

In a further aspect, a photovoltaic module includes a first photovoltaiccell including an electrode with a first surface, a second photovoltaiccell including an electrode with a second surface, and an interconnect(e.g., an electrically conductive interconnect) that connects (e.g.,electrically connects and/or mechanically connects) the first and secondphotovoltaic cells. The interconnect is supported by the first andsecond surfaces.

In an additional aspect, a module includes first and second photovoltaiccells. The efficiency of the module is at least about 80% of theefficiency of one of the photovoltaic cells.

In an additional aspect, a method includes making one or more of thepreceding modules via a continuous process.

In another aspect, a method includes making one or more of the precedingmodules via a roll-to-roll process.

Embodiments can provide one or more of the following advantages.

In some embodiments, the interconnects can connect (e.g., seriallyconnect) two or more photovoltaic cells with little ohmic loss. This canbe particularly desirable when trying to maximize voltage, amperageand/or power output from photovoltaic cells and modules.

In certain embodiments, the interconnects can connect (e.g., seriallyconnect) two or more photovoltaic cells together with little or noincrease in fill-factor and little or no decrease in efficiency ascompared to a single photovoltaic cell.

In some embodiments, the interconnects can mechanically connect adjacentphotovoltaic cells together, thereby reducing (e.g., eliminating) theuse seals (e.g., seals including) adhesives within photovoltaic modules.This can enhance the useful lifetime of a module by, for example,reducing the amount and/or presence of one or more materials that can bereactive with one or more of the components contained in a photovoltaiccell, and/or by, for example, reducing (e.g., eliminating) leak pathspresent in a module.

In certain embodiments, the interconnects can provide a robustmechanical and/or highly electrically conductive connection between thecathode of the first photovoltaic cell and the anode of the secondphotovoltaic cell.

In embodiments that include an interconnect in the shape of a mesh, themesh in the interconnect can form multiple points of electrical contactwith each electrode. Having multiple points of contact between theelectrodes can increase the electrical conductivity between electrodesby providing a larger area and volume for electrical current to passbetween electrodes via the interconnect. Alternatively or additionally,having multiple points of contact between the electrodes can enhance thestability of the flow of electrons between electrodes via theinterconnect. For example, under certain circumstances, a module may beflexed or bent, which can temporarily or permanently break a point ofcontact between the interconnect and one of the electrodes. Theresulting reduction in electrical conductivity between electrodes isreduced when multiple points of electrical contact are present.

In embodiments that include an interconnect in the shape of a mesh, themesh can be formed of relatively fine strands without substantialdifficulty.

In embodiments that include an interconnect in the shape of a mesh, theabsolute height of the metal mesh can set the gap/space between theelectrodes, and allow for this gap/space to be relatively small.

In embodiments that include an interconnect that includes an adhesive,the adhesive can enhance the mechanical integrity of the interconnectby, for example, providing multiple points of adhesive bonding betweenthe electrodes in adjacent photovoltaic cells in the module.Alternatively or additionally, the adhesive can provide electricalinsulation between certain components of the module that are not desiredto be in electrical contact.

In some embodiments, the modules can provide good electrical contactbetween electrodes in adjacent photovoltaic cells without the presenceof a separate interconnect to provide the electrical communication. Thiscan reduce the cost and/or complexity associated with manufacture of themodules. For example, by forming the shaped (e.g., dimpled) portions ofthe cathode (and/or anode) during the process of manufacturing themodule, the complexity of aligning various portions of the module can bereduced.

In certain embodiments, an oxide film can form on the surface of thecathode during processing (e.g., sintering of the titania). In suchembodiments, the process of shaping the portions of the cathode canbreak the oxide film, which can enhance the electrical conductivitybetween the cathode and the anode.

In some embodiments, the potential surface area of theadhesive/substrate bond can be relatively high, which can enhance thebond strength and reliability of the photovoltaic cell.

In certain embodiments, a module can include fewer components, which canenhance reliability and/or reduce cost.

In some embodiments, one or more of the materials that form aninterconnect are commercially available in compositions that aresubstantially inert to other components of the module (e.g., theelectrolyte(s)).

In certain embodiments, a module can include flexible substrates ofphotovoltaic cells are electrically and mechanically connected to form aflexible module which is well suited for wide-ranging implementations.

In some embodiments, an interconnect can electrically and/ormechanically interconnect one or more photovoltaic cells (e.g., one ormore adjacent photovoltaic cells) to formed a photovoltaic module havingenhanced stability, enhanced reliability, reduced inactive area betweenphotovoltaic cells (e.g., adjacent photovoltaic cells), and/or reducedinactive volume between photovoltaic cells (e.g., adjacent photovoltaiccells).

Features and advantages are set forth in the description, drawings andclaims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of an embodiment of a photovoltaicmodule including two photovoltaic cells.

FIG. 2A is a cross-sectional view of another embodiment of aphotovoltaic module.

FIG. 2B is a bottom view of the photovoltaic module of FIG. 2A.

FIG. 3 is a cross-sectional view of an embodiment of a photovoltaicmodule including three photovoltaic cells.

FIG. 4 is a cross-sectional view of another embodiment of a photovoltaicmodule including three photovoltaic cells.

FIG. 5 is a cross-sectional view of an embodiment of a photovoltaicmodule.

FIG. 6 is a cross-sectional view of a portion of the photovoltaic moduleof FIG. 5.

FIG. 7 is a cross-sectional view through a portion of the interconnectin the photovoltaic module in a direction perpendicular to thecross-section shown in FIGS. 5 and 6.

FIG. 8A is a side view of a photovoltaic module including three cells ina series configuration.

FIG. 8B is a detail view of the interconnect between adjacent cell inFIG. 8A.

FIG. 9A is a side view of a photovoltaic module including seven cells ina series configuration including an interconnect paste positionedbetween the anode of one cell and the cathode of an adjacent cell.

FIG. 9B is a side view of FIG. 9A with the paste pressed into place.

FIG. 10 is a cross-sectional view of an embodiment of a photovoltaicmodule.

FIG. 11 is a perspective view of the cathode in the photovoltaic modulein a direction perpendicular to the cross-section in FIG. 10.

FIG. 12 is a cross-sectional view of an embodiment of a photovoltaicmodule.

FIG. 13 is a cross-section view of a portion of the photovoltaic cellshown in FIG. 12.

FIG. 14 is a cross-sectional view of another embodiment of aphotovoltaic module.

FIG. 15 is a perspective view of the cathode in the photovoltaic modulein a direction perpendicular to the cross-section in FIG. 14.

FIG. 16 is a cross-sectional view of an embodiment of a DSSC.

FIG. 17 is a schematic representation of an embodiment of a method ofmaking a DSSC.

FIG. 18 is a cross-sectional view of a polymer photovoltaic cell.

FIG. 19 shows a structure including a photovoltaic module.

FIG. 20 shows a structure including a photovoltaic module.

FIG. 21 shows a structure including a photovoltaic module.

FIG. 22 graphically depict the efficiencies for two individual cells anda module formed by the composite of the two cells.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

In general, the description relates to photovoltaic modules formed byelectrically and/or mechanically connecting one or more photovoltaiccells (e.g., one or more adjacent photovoltaic cells) using one or moreinterconnects. Embodiments of such modules are described below.

In some embodiments, the efficiency of a photovoltaic module can be atleast about 80% (e.g., at least about 85%, at least about 90%, at leastabout 95%, at least about 98%) of the efficiency of one or more of thephotovoltaic cells contained in the photovoltaic module.

As referred to herein, the efficiency of a photovoltaic cell is measuredas follows. The photovoltaic cell is exposed to an A.M. 1.5 (100 mW persquare cm) light source (Oriel Solar Simulator) for 30 seconds. Thecurrent generated within the photovoltaic cell is measured and plottedagainst voltage to determine the efficiency of the photovoltaic cell.

As used herein, the efficiency of a photovoltaic module is measured asfollows. The photovoltaic module is exposed to an A.M. 1.5 (100 mW persquare cm) light source (Oriel Solar Simulator) for 30 seconds. Thecurrent generated within the photovoltaic module is measured and plottedagainst voltage to determine the efficiency of the photovoltaic module.

FIG. 1 shows a cross-sectional view of a photovoltaic module 100 thatincludes an electrically conductive interconnect 105 that connects afirst photovoltaic cell 110 to a second photovoltaic cell 115. Theelectrically conductive interconnect 105 can include a stitch, in oneexample. Photovoltaic cell 110 includes a cathode 120, a photoactivelayer 122, a charge carrier layer 124, an anode 126, and a substrate128. Similarly, photovoltaic cell 115 includes a cathode 140, aphotoactive layer 142, a charge carrier layer 144, an anode 146, and asubstrate 148. Photovoltaic cells 110 and 115 are positioned withrespect to each other in a step-wise configuration, such that a portion155 of photovoltaic cell 110 overlaps a portion 160 of photovoltaic cell115, thereby forming an overlapping region 165. An electricallyconductive interconnect 105 is disposed within overlapping region 165 toprovide an electrically conductive path from cathode 120 to anode 146.

In general, electrically conductive interconnect 105 is sized to createan electrically conductive and continuous path from cathode 120 to anode146. For example, in some embodiments, electrically conductiveinterconnect 105 is sized to extend through cathode 120, substrate 148and anode 146 within overlapping region 165. In certain embodiments,electrically conductive interconnect 105 has a length of at least about30 microns and/or at most about 500 microns (e.g., a length of fromabout 100 microns to about 200 microns).

Generally, the width of electrically conductive interconnect 105 can beselected as desired. In some embodiments, the width of electricallyconductive interconnect 105 is selected so that the width of overlappingregion 165 is relatively small. For example, in certain embodiments, thewidth of electrically conductive interconnect 105 is less than about1500 microns (e.g., less than about 1000 microns, less than about 500microns). Typically, electrically conductive interconnect 105 is atleast about 100 microns wide. Reducing the width of the overlappingregion 165 can be particularly desirable when trying to increase theavailable photoactive area within photovoltaic cells 110 and 115. Forexample, as the width of overlapping region 165 decreases, the area ofthe active region of module 100 increases.

In general, electrically conductive interconnect 105 can be made fromany electrically conductive material. As referred to herein, anelectrically conductive material has a conductivity of at least about 10(Ω-cm)⁻¹ at 25° C. Typically, the material(s) used to form electricallyconductive interconnect 105 is relatively strong so as to securephotovoltaic cell 110 to photovoltaic cell 115. Exemplary materials forforming electrically conductive interconnects 105 include, for example,metals, such as, copper and titanium, and alloys, such as, steel,tin-lead alloys, tin-bismuth alloys, lead-bismuth alloys,tin-bismuth-lead alloys. In certain embodiments, electrically conductiveinterconnect 105 can be formed of a material (e.g., a polymer fiber,such a nylon fiber, a polyester fiber, a Kevlar fiber, an Orlon fiber)that is coated with a metal or an alloy. In some embodiments,electrically conductive interconnect 105 is formed of a metal or analloy coated with a low temperature solder, such as, for example, atin-lead alloy, a tin-bismuth alloy, a lead-bismuth alloy, or atin-bismuth-lead alloy. In certain embodiments, electrically conductiveinterconnect is formed of a metal or an alloy that is coated with anepoxy, such as, for example, a silver based epoxy.

Referring to FIGS. 2A and 2B, interconnects 200, which may beelectrically conductive or electrically insulating, (e.g., electricallyconductive and/or electrically insulating stitches) can be used tosecure terminal contacts 205 (e.g., metal tapes, thin metal foils, andmetal braids) to the electrodes at the ends of photovoltaic module 100(e.g., at anode 126 and at cathode 140). Terminal contacts 205 aretypically used as a connection site between photovoltaic modules andelectric devices, so that the electricity generated within thephotovoltaic module can be used to drive connected electric devices.

In general, interconnects 200 can be made from any desired material.Typically, interconnects 200 are made from a material that is strongenough to secure the terminal contact to the desired electrode.Exemplary materials used for forming interconnects 200 include thosenoted above with respect to electrically conductive interconnect 105,and polymers.

While photovoltaic module 100 has been described as including twophotovoltaic cells, a photovoltaic module can include more than two(e.g., three, four, five, six, seven) photovoltaic cells. For example,as shown in FIG. 3, a photovoltaic module 200 includes a firstphotovoltaic cell 180, a second photovoltaic cell 185 and a thirdphotovoltaic cell 190. An electrically conductive interconnect 192 isused to join the cathode of photovoltaic cell 180 with the anode ofphotovoltaic cell 185, and a second electrically conductive interconnect194 is used to join the cathode of photovoltaic cell 185 with the anodeof photovoltaic cell 190.

While photovoltaic cells have been described as being positioned in astep-wise fashion with respect to each other to form an overlappingregion in adjacent cells, in some embodiments, the photovoltaic cells ina photovoltaic module have a different arrangement. FIG. 4 shows aphotovoltaic module 220 that includes photovoltaic cells 210, 212, and214 that share a common substrate 290. Photovoltaic cells 210, 212, and214 each include a photoactive layer 280 and a charge carrier layer 285disposed between a cathode 270 and an anode 275. Regions 295 ofelectrically insulating material (e.g., formed of an adhesive) arepositioned between cells 210 and 212 and between cells 212 and 214. Aportion of cathode 270 of cell 210 overlaps a portion of anode 275 ofcell 212 to form an overlapping region 265 within which electricallyconductive interconnect 105 is positioned (in substrate 290, in anode275 of cell 212, in region 295 between cells 210 and 212, in cathode 270of cell 210, and in substrate 300). Likewise, a portion of cathode 270of cell 212 overlaps a portion of anode 275 of cell 214 to form anoverlapping region 267 within which electrically conductive interconnect105 is positioned (in substrate 290, in anode 275 of cell 214, in region295 between cells 212 and 214, in cathode 270 of cell 212, and insubstrate 300).

FIG. 5 shows a module 300 that includes photovoltaic cells 310, 320 and330 that share common substrates 340 and 345. Each photovoltaic cellincludes cathode 350, a photoactive layer 360, a charge carrier layer370 and an anode 380.

As shown in FIGS. 6 and 7, interconnect 301 is formed of a mesh 305 andan electrically insulative material 390. Mesh 305 has electricallyconductive regions 385 and open regions 387, and electrically insulativematerial 390 is disposed in open regions 387 of mesh 305. An uppersurface 393 of mesh 305 contacts anode 380, and a lower surface 395 ofmesh 305 contacts cathode 350. With this arrangement, electrodes 350 and380 in adjacent cells are electrically connected in the directionbetween electrodes 350 and 380 via regions 385 of mesh 305, whileadjacent photovoltaic cells are electrically insulated from each otherby adhesive material 397 in the perpendicular plane.

Mesh 305 can be prepared in various ways. In some embodiments, mesh 305is an expanded mesh. An expanded metal mesh can be prepared, forexample, by removing regions 387 (e.g., via laser removal, via chemicaletching, via puncturing) from a sheet of material (e.g., an electricallyconductive material, such as a metal or an alloy), followed bystretching the sheet (e.g., stretching the sheet in two dimensions). Incertain embodiments, mesh 305 is a metal sheet formed by removingregions 387 (e.g., via laser removal, via chemical etching, viapuncturing) without subsequently stretching the sheet. In someembodiments, mesh 305 is a woven mesh formed by weaving wires ofmaterial that form solid regions 385. The wires can be woven using, forexample, a plain weave, a Dutch, weave, a twill weave, a Dutch twillweave, or combinations thereof. In certain embodiments, mesh 305 isformed of a welded wire mesh.

In general, solid regions 385 are formed entirely of an electricallyconductive material (e.g., regions 385 are formed of a substantiallyhomogeneous material that is electrically conductive). Examples ofelectrically conductive materials that can be used in regions 385include electrically conductive metals, electrically conductive alloysand electrically conductive polymers. Exemplary electrically conductivemetals include gold, silver, copper, nickel, palladium, platinum andtitanium. Exemplary electrically conductive alloys include stainlesssteel (e.g., 332-stainless steel, 316-stainless steel), alloys of gold,alloys of silver, alloys of copper, alloys of nickel, alloys ofpalladium, alloys of platinum and alloys of titanium. Exemplaryelectrically conducting polymers include polythiophenes (e.g.,poly(3,4-ethelynedioxythiophene) (PEDOT)), polyanilines (e.g., dopedpolyanilines), polypyrroles (e.g., doped polypyrroles). In someembodiments, combinations of electrically conductive materials are used.

In some embodiments, solid regions 385 are formed of a material that iscoated with a different material (e.g., using metallization, using vapordeposition). In general, the inner material can be formed of any desiredmaterial (e.g., an electrically insulative material, an electricallyconductive material, or a semiconductive material), and the outermaterial is an electrically conductive material. Examples ofelectrically insulative material from which the inner material can beformed include textiles, optical fiber materials, polymeric materials(e.g., a nylon) and natural materials (e.g., flax, cotton, wool, silk).Examples of electrically conductive materials from which the outermaterial can be formed include the electrically conductive materialsdisclosed above. Examples of semiconductive materials from which theouter material can be formed include indium tin oxide, fluorinated tinoxide, tin oxide and zinc oxide. In some embodiments, the inner materialis in the form of a fiber, and the outer material is an electricallyconductive material that is coated on the inner material. In certainembodiments, the inner material is in the form of a mesh (see discussionabove) that, after being formed into a mesh, is coated with the outermaterial. As an example, the inner material can be an expanded metalmesh, and the outer material can be PEDOT that is coated on the expandedmetal mesh.

Typically, the maximum thickness of mesh 305 in a directionsubstantially perpendicular to the surfaces of substrates 340 and 345 isat least 10 microns (e.g., at least about 15 microns, at least about 25microns, at least about 50 microns) and/or at most about 250 microns(e.g., at most about 200 microns, at most about 150 microns, at mostabout 100 microns, at most about 75 microns).

While shown in FIG. 7 cross-sectional shape, open regions 387 cangenerally have any desired shape (e.g., square, circle, semicircle,triangle, ellipse, trapezoid, irregular shape). In some embodiments,different open regions 387 in mesh 305 can have different shapes.

Although shown in FIG. 7 as forming a diamond design, solid regions 385can generally form any desired design (e.g., rectangle, circle,semicircle, triangle, ellipse, trapezoid, irregular shape). In someembodiments, different solid regions 385 in mesh 305 can have differentshapes.

FIGS. 8A and 8B show a photovoltaic module 500 that includesphotovoltaic cells 505, 510 and 515 that are positioned in a step-wiseconfiguration with respect to each other. A portion 525 of photovoltaiccell 515 overlaps a portion 520 of photovoltaic cell 510. Similarly, aportion 533 of photovoltaic cell 510 overlaps a portion 535 ofphotovoltaic cell 505. A cathode 540 of cell 505 is electricallyconnected to an anode 545 of adjacent cell 505 by wrapping the edge ofthe anode 545 with an electrically conductive tape 547. In someembodiments, the tape 547 can be sized to contact the entire back faceof the cathode 540 and thus provide a mechanical attachment betweenadjacent cells or only a portion of the cathode 540. In embodiments inwhich the tape 547 does not cover all of the back face of the cathode540, the exposed portion of the back face of the cathode 540 can beoptionally coated with a non-conductive adhesive to supplement theattachment to the anode 545 to the adjacent cell 505.

While element 547 has been described as a conductive tape, moregenerally, element 547 can be any kind of electrically conductiveelement having the general structure described. In some embodiments,elements 547 is in the form of a coating.

FIG. 9A shows a photovoltaic module 550 that includes seven overlappingcells 555 a-555 g arranged in step-wise configuration. Interconnect 560a is applied parallel to an edge of the cell 555 a along the anode 565 afor electrical and mechanical connection to the cathode 570 of adjacentcell 555 b. Similarly, interconnects 560 b-560 f connect overlappingcells 555 b and 555 c, 555 c and 555 d, 555 d and 555 e, 555 e and 555f, and 555 f and 555 g. FIG. 9B shows the interconnects 560 pressed intoplace to connect adjacent cells. In general, interconnects 560 can beformed of any appropriate electrically conductive material. In someembodiments, one or more interconnects 560 are formed of a bead of aconductive paste. Optionally, one or more of the interconnects 560 canbe formed with a thermoplastic conductive ribbon, solder and/or fiber.Typically, in such embodiments, the material forming interconnect 560 ispositioned parallel to the edge of one cell so that after applying theappropriate amount of heat and pressure, the interconnect is distributedover the cathode of one cell and the anode of an adjacent cell.

One or more of interconnects 560 a-560 f can be formed by a process thatdoes not involve the use of heat or pressure (e.g., ink jet printing,painting/drying). Optionally, a thermal transfer process can be used toform one or more of interconnects 560 a-560 f.

In certain embodiments, one or more of interconnects 560 a-560 f can beformed of a mesh (e.g., an adhesive mesh), as described herein.

FIG. 10 shows a photovoltaic module 3100 that includes photovoltaiccells 3110, 3120, and 3130 that share common substrates 3140 and 3145.Each photovoltaic cell includes an adhesive 3147, a cathode 3150, aphotoactive layer 3160, a charge carrier layer 3170, a anode 3180 and anadhesive 3190. Cathode 3150 includes a shaped (e.g., dimpled, embossed)portion 3152 configured to extend through adhesive 3190 and makeelectrical contact with anode 3180. As shown in FIG. 11, cathode 3150has multiple shaped portions 3152 with non-shaped portions therebetween.With this arrangement, shaped portions 3152 of cathode 3150 form anelectrical connection between cathode 3150 and anode 3180 without usinga separate interconnect component.

Although shown in FIG. 11 as being circular, more generally shapedportions 3152 can have any desired shape (e.g., square, circle,semicircle, triangle, ellipse, trapezoid, corrugated, such assinusoidally corrugated, irregular shape).

Generally, cathodes 3150 are formed of a relatively thin, electricallyconductive layer. In some embodiments, cathodes 3150 are formed of ametal or an alloy (e.g., titanium or indium) foil. In certainembodiments, cathodes are formed of a relatively thin layer of a plastic(see discussion regarding substrates 3140 and 3145 below) that has asurface coated with an electrically conductive material (e.g., a metalor an alloy, such as titanium or indium). Shaped portions 3152 can beformed using a variety of techniques, including standard foil embossingtechniques. For example, in certain embodiments, shaped portions 3152can be formed by running foil 3150 under a sewing machine with a bluntedneedle. As another example, in some embodiments, shaped portions 3152can be formed by passing foil 3150 over a spinning wheel havingprotrusions (e.g., dimples). Shaped portions 3152 can be formed in foil3150 before being incorporated into module 3100, or shaped portions 3152can be formed in foil 3150 as module 3100 is being manufactured (seediscussion below). In general electrode 3150 is substantially flat,except for embossments 3152. Although embossments 3152 can generallyhave any desired shape, embossments 3152 typically have a slight radius(e.g., so that forming embossments 3152 does not result in the formationof holes in electrode 3150).

FIGS. 12 and 13 show a partially exploded view of a photovoltaic module8000 that includes photovoltaic cells 8100, 8200, 8300 and 8400. Eachcell includes a cathode side 8010 and an anode side 8020. Each cathodeside 8010 includes substrate 8012, an adhesive layer 8014 (e.g., a foiladhesive, such as a one mil thick foil adhesive), an electricallyconductive layer 8016 (e.g., a metal layer, such as a two mils thicktitanium foil) and a photoactive layer 8018 (e.g., a dye sensitizedtitania layer). Each anode side includes substrate 8020 and a catalystlayer 8022 (e.g., a platinum-containing catalyst layer). In cells 8100,8200 and 8300, a region 8017 of each portion of layer 8016 is shaped(e.g., embossed, dimpled) and there is a gap 8019 between layers 8016 inadjacent photovoltaic cells.

Module 8000 further includes an electrically conductive bridge 8026that, after assembly of module 8000, is in direct contact withcorresponding portion 8017 of corresponding layer 8016, therebyproviding an electrical connection. Bridges 8026 are typically compliantand electrically conductive. For example, bridges 8026 can be formed ofa compliant polymer matrix containing electrically conductive particles(e.g., at sufficient loading to impart sufficient electricalconductivity to bridges 8026). In some embodiments, one or more bridges8026 can contain titanium (e.g., in the form of a titanium composite).Although shown as separate components in the exploded views of FIGS. 12and 13, in some embodiments, bridges 8026 can be disposed directly oncorresponding portions 8017 of corresponding layers 8016. For example, abridge 8026 can be printed onto a corresponding portion 8017 ofcorresponding layer 8016.

Module 8000 also includes seals 8028 and 8029. Seals 8028 and 8029reduce leaking of components (e.g., between adjacent cells) and/orreduce corrosion of components (e.g., if moisture gets into one or morecells). When module 8000 is assembled, the upper and lower ends of seal8029 contact layers 8014 and 8022, respectively, and the upper and lowerends of seal 8028 contacts layers 8026 and 8022, respectively. Seals8028 and 8029 are generally formed of an adhesive material, such asthose described herein, and may optionally containing one or morestructural components (e.g., one more beads). In embodiments, in whichseals 8028 and/or 8029 contain one or more structural components, thestructural components are typically electrically nonconductive and/or atsufficiently low loading so that seals 8028 and/or 8029 are electricallynonconductive.

Module 8000 further includes end seals 8030 and 8032 (e.g., adhesive endseals).

Without wishing to be bound by theory, it is believed that moduleshaving the general design illustrates in FIGS. 12 and 13 can allow for arelatively thin photovoltaic module, that still provides good electricalpower and efficiency. It is believed that the use of multiple adhesivelayers (e.g., seals 8028 and 8029) can provide an advantage in thatconstruction of the module can be achieved without pushing a portion ofa layer through an adhesive. This can also reduce the possibility ofscratching one of the electrodes, which can result in a localized areaof reduced electrical conductivity.

FIG. 14 shows a photovoltaic module 4000 in which cathode 3350 has abent end 3352 configured to extend through adhesive 3190 and makeelectrical contact with anode 3180. As shown in FIG. 15, bent end 3352forms a cathode forms a line. With this arrangement, bent end 3352 ofcathode 3350 form an electrical connection between cathode 3350 andanode 3180 without using a separate interconnect component.

Although shown in FIG. 15 as being continuous, in some embodiments, bentend 3352 can be noncontinuous (e.g., when viewed as shown in FIG. 15,there can be alternating portions of cathode 3350 having a bent end).

Further, although the cathodes have been described as being formed of afoil formed of certain materials, in some embodiments, one or more ofthe primary foils can be formed of a different material. In someembodiments, the cathodes can be formed of a foil of a transparentelectrically conductive material, such as. Examples of such materialsinclude certain metal oxides, such as indium tin oxide (ITO), tin oxide,a fluorine-doped tin oxide, and zinc-oxide.

In certain other embodiments, the cathodes can be a discontinuous layerof an electrically conductive material, such as an electricallyconducting mesh. Suitable mesh materials include metals, such aspalladium, titanium, platinum, stainless steel and alloys thereof. Themesh material can include a metal wire. The electrically conductive meshmaterial can also include an electrically insulating material that hasbeen coated with an electrically conductive material, such as metal. Theelectrically insulating material can include a fiber, such as a textilefiber or an optical fiber. Examples of textile fibers include syntheticpolymer fibers (e.g., nylons) and natural fibers (e.g., flax, cotton,wool, and silk). The mesh electrode can be flexible to facilitate, forexample, formation of a photovoltaic cell by a continuous manufacturingprocess.

A mesh cathode can take a wide variety of forms with respect to, forexample, wire (or fiber) diameters and mesh densities (i.e., the numberof wire (or fiber) per unit area of the mesh). The mesh can be, forexample, regular or irregular, with any number of opening shapes (e.g.,square, circle, semicircle, triangular, diamond, ellipse, trapezoid,and/or irregular shapes). Mesh form factors (such as, e.g., wirediameter and mesh density) can be chosen, for example, based on theelectrical conductivity of the wire (or fibers) of the mesh, the desiredoptical transmissivity, based on the electrical conductivity of thewires (or fibers) of the mesh, the desired optical transmissivity,flexibility, and/or mechanical strength. Typically, the mesh electrodeincludes a wire (or fiber) mesh with an average wire (or fiber) diameterin the range from about 1 micron to about 400 microns, and an averageopen area between wires (or fibers) in the range from about 60% to about95%. A mesh electrode can be formed using a variety of techniques, suchas, for example, ink jet printing, lithography and/or ablation (e.g.,laser ablation). In some embodiments, a mesh electrode can be formed ofan expanded metal mesh. Mesh electrodes are discussed in U.S. patentapplication Ser. No. 10/395,823, filed Mar. 23, 2003 and in U.S. patentapplication Ser. No. 10/723,554, filed Nov. 26, 2003.

Adhesives 3147 and 3190 can generally be formed of any electricallyinsulative adhesive. Examples of such adhesives include co-polymers ofolefins, acrylates, and urethanes, and other hotmelt adhesives. Examplesof commercially available adhesives include Bynel® adhesives (availablefrom DuPont), thermobond adhesive 845 (available from 3M) and Dyneon™THV220 fluoropolymer adhesive (available from 3M).

DSSCs

In some embodiments, a photovoltaic cell is a DSSC. FIG. 16 is across-sectional view of a DSSC 4300 including substrates 4310 and 4370,electrically conductive layers (electrodes) 4320 and 4360, a catalystlayer 4330, a charge carrier layer 4340, and a photoactive layer 4350.

Photoactive layer 4350 generally includes one or more dyes and asemiconductor material associated with the dye.

Examples of dyes include black dyes (e.g.,tris(isothiocyanato)-ruthenium (II)-2,2′:6′,2″-terpyridine-4,4′,4″-tricarboxylic acid, tris-tetrabutylammoniumsalt), orange dyes (e.g., tris(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium (II) dichloride, purple dyes (e.g.,cis-bis(isothiocyanato)bis-(2,2′-bipyridyl-4,4′-dicarboxylato)-ruthenium(II)), red dyes (e.g., an eosin), green dyes (e.g., a merocyanine) andblue dyes (e.g., a cyanine). Examples of additional dyes includeanthocyanines, porphyrins, phthalocyanines, squarates, and certainmetal-containing dyes.

In some embodiments, photoactive layer 4350 can include multipledifferent dyes that form a pattern. Examples of patterns includecamouflage patterns, roof tile patterns and shingle patterns. In someembodiments, the pattern can define the pattern of the housing aportable electronic device (e.g., a laptop computer, a cell phone). Incertain embodiments, the pattern provided by the photovoltaic cell candefine the pattern on the body of an automobile. Patterned photovoltaiccells are disclosed, for example, in co-pending and commonly owned U.S.Ser. No. 60/638,070, filed Dec. 21, 2004, which is hereby incorporatedby reference.

Examples of semiconductor materials include materials having the formulaM_(x)O_(y), where M may be, for example, titanium, zirconium, tungsten,niobium, lanthanum, tantalum, terbium, or tin and x and y are integersgreater than zero. Other suitable materials include sulfides, selenides,tellurides, and oxides of titanium, zirconium, tungsten, niobium,lanthanum, tantalum, terbium, tin, or combinations thereof. For example,TiO₂, SrTiO₃, CaTiO₃, ZrO₂, WO₃, La₂O₃, Nb₂O₅, SnO₂, sodium titanate,cadmium selenide (CdSe), cadmium sulphides, and potassium niobate may besuitable materials.

Typically, the semiconductor material contained within layer 4350 is inthe form of nanoparticles. In some embodiments, the nanoparticles havean average size between about two nm and about 100 nm (e.g., betweenabout 10 nm and 40 nm, such as about 20 nm). Examples of nanoparticlesemiconductor materials are disclosed, for example, in co-pending andcommonly owned U.S. Ser. No. 10/351,249, which is hereby incorporated byreference.

The nanoparticles can be interconnected, for example, by hightemperature sintering, or by a reactive linking agent.

In certain embodiments, the linking agent can be a non-polymericcompound. The linking agent can exhibit similar electronic conductivityas the semiconductor particles. For example, for TiO₂ particles, theagent can include Ti—O bonds, such as those present in titaniumalkoxides. Without wishing to be bound by theory, it is believed thattitanium tetraalkoxide particles can react with each other, with TiO₂particles, and with a conductive coating on a substrate, to formtitanium oxide bridges that connect the particles with each other andwith the conductive coating (not shown). As a result, the cross-linkingagent enhances the stability and integrity of the semiconductor layer.The cross-linking agent can include, for example, an organometallicspecies such as a metal alkoxide, a metal acetate, or a metal halide. Insome embodiments, the cross-linking agent can include a different metalthan the metal in the semiconductor. In an exemplary cross-linking step,a cross-linking agent solution is prepared by mixing a sol-gel precursoragent, e.g., a titanium tetra-alkoxide such as titanium tetrabutoxide,with a solvent, such as ethanol, propanol, butanol, or higher primary,secondary, or tertiary alcohols, in a weight ratio of 0-100%, e.g.,about 5 to about 25%, or about 20%. Generally, the solvent can be anymaterial that is stable with respect to the precursor agent, e.g., doesnot react with the agent to form metal oxides (e.g. TiO₂). The solventpreferably is substantially free of water, which can cause precipitationof TiO₂. Such linking agents are disclosed, for example, in publishedU.S. Patent Application 2003-0056821, which is hereby incorporated byreference.

In some embodiments, a linking agent can be a polymeric linking agent,such as poly(n-butyl titanate. Examples of polymeric linking agents aredisclosed, for example, in co-pending and commonly owned U.S. Ser. No.10/350,913, which is hereby incorporated by reference.

Linking agents can allow for the fabrication of an interconnectednanoparticle layer at relatively low temperatures (e.g., less than about300° C.) and in some embodiments at room temperature. The relatively lowtemperature interconnection process may be amenable to continuous (e.g.,roll-to-roll) manufacturing processes using polymer substrates.

The interconnected nanoparticles are generally photosensitized by thedye(s). The dyes facilitates conversion of incident light intoelectricity to produce the desired photovoltaic effect. It is believedthat a dye absorbs incident light resulting in the excitation ofelectrons in the dye. The energy of the excited electrons is thentransferred from the excitation levels of the dye into a conduction bandof the interconnected nanoparticles. This electron transfer results inan effective separation of charge and the desired photovoltaic effect.Accordingly, the electrons in the conduction band of the interconnectednanoparticles are made available to drive an external load.

The dye(s) can be sorbed (e.g., chemisorbed and/or physisorbed) on thenanoparticles. A dye can be selected, for example, based on its abilityto absorb photons in a wavelength range of operation (e.g., within thevisible spectrum), its ability to produce free electrons (or electronholes) in a conduction band of the nanoparticles, its effectiveness incomplexing with or sorbing to the nanoparticles, and/or its color.

In some embodiments, photoactive layer 4350 can further include one ormore co-sensitizers that adsorb with a sensitizing dye to the surface ofan interconnected semiconductor oxide nanoparticle material, which canincrease the efficiency of a DSSC (e.g., by improving charge transferefficiency and/or reducing back transfer of electrons from theinterconnected semiconductor oxide nanoparticle material to thesensitizing dye). The sensitizing dye and the co-sensitizer may be addedtogether or separately when forming the photosensitized interconnectednanoparticle material. The co-sensitizer can donate electrons to anacceptor to form stable cation radicals, which can enhance theefficiency of charge transfer from the sensitizing dye to thesemiconductor oxide nanoparticle material and/or can reduce backelectron transfer to the sensitizing dye or co-sensitizer. Theco-sensitizer can include (1) conjugation of the free electron pair on anitrogen atom with the hybridized orbitals of the aromatic rings towhich the nitrogen atom is bonded and, subsequent to electron transfer,the resulting resonance stabilization of the cation radicals by thesehybridized orbitals; and/or (2) a coordinating group, such as a carboxyor a phosphate, the function of which is to anchor the co-sensitizer tothe semiconductor oxide. Examples of suitable co-sensitizers includearomatic amines (e.g., color such as triphenylamine and itsderivatives), carbazoles, and other fused-ring analogues. Examples ofphotoactive layers including co-sensitizers are disclosed, for example,in co-pending and commonly owned U.S. Ser. No. 10/350,919, which ishereby incorporated by reference.

In some embodiments, photoactive layer 4350 can further includemacroparticles of the semiconductor material, where at least some of thesemiconductor macroparticles are chemically bonded to each other, and atleast some of the semiconductor nanoparticles are bonded tosemiconductor macroparticles. The dye(s) are sorbed (e.g., chemisorbedand/or physisorbed) on the semiconductor material. Macroparticles refersto a collection of particles having an average particle size of at leastabout 100 nanometers (e.g., at least about 150 nanometers, at leastabout 200 nanometers, at least about 250 nanometers). Examples ofphotovoltaic cells including macroparticles in the photoactive layer aredisclosed, for example, in co-pending and commonly owned U.S. Ser. No.60/589,423, which is hereby incorporated by reference.

In certain embodiments, a DSSC can include a coating that can enhancethe adhesion of a photovoltaic material to a base material (e.g., usingrelatively low process temperatures, such as less than about 300° C.).Such photovoltaic cells and methods are disclosed, for example, inco-pending and commonly owned U.S. Ser. No. 10/351,260, which is herebyincorporated by reference.

The composition and thickness of electrically conductive layer 4320 isgenerally selected based on desired electrical conductivity, opticalproperties, and/or mechanical properties of the layer. In someembodiments, layer 4320 is transparent. Examples of transparentmaterials suitable for forming such a layer include certain metaloxides, such as indium tin oxide (ITO), tin oxide, and a fluorine-dopedtin oxide. In some embodiments, electrically conductive layer 4320 canbe formed of a foil (e.g., a titanium foil). Electrically conductivelayer 4320 may be, for example, between about 100 nm and 500 nm thick,(e.g., between about 150 nm and 300 nm thick).

In certain embodiments, electrically conductive layer 4320 can be opaque(i.e., can transmit less than about 10% of the visible spectrum energyincident thereon). For example, layer 4320 can be formed from acontinuous layer of an opaque metal, such as copper, aluminum, indium,or gold. In some embodiments, an electrically conductive layer can havean interconnected nanoparticle material formed thereon. Such layers canbe, for example, in the form of strips (e.g., having a controlled sizeand relative spacing, between first and second flexible substrates).Examples of such DSSCs are disclosed, for example, in co-pending andcommonly owned U.S. Ser. No. 10/351,251, which is hereby incorporated byreference.

In some embodiments, electrically conductive layer 4320 can include adiscontinuous layer of an electrically conductive material. For example,electrically conductive layer 4320 can include an electricallyconducting mesh. Suitable mesh materials include metals, such aspalladium, titanium, platinum, stainless steels and alloys thereof. Insome embodiments, the mesh material includes a metal wire. Theelectrically conductive mesh material can also include an electricallyinsulating material that has been coated with an electrically conductingmaterial, such as a metal. The electrically insulating material caninclude a fiber, such as a textile fiber or monofilament. Examples offibers include synthetic polymeric fibers (e.g., nylons) and naturalfibers (e.g., flax, cotton, wool, and silk). The mesh electricallyconductive layer can be flexible to facilitate, for example, formationof the DSSC by a continuous manufacturing process. Photovoltaic cellshaving mesh electrically conductive layers are disclosed, for example,in co-pending and commonly owned U.S. Ser. Nos. 10/395,823; 10/723,554and 10/494,560, each of which is hereby incorporated by reference.

The mesh electrically conductive layer may take a wide variety of formswith respect to, for example, wire (or fiber) diameters and meshdensities (i.e., the number of wires (or fibers) per unit area of themesh). The mesh can be, for example, regular or irregular, with anynumber of opening shapes. Mesh form factors (such as, e.g., wirediameter and mesh density) can be chosen, for example, based on theconductivity of the wire (or fibers) of the mesh, the desired opticaltransmissivity, flexibility, and/or mechanical strength. Typically, themesh electrically conductive layer includes a wire (or fiber) mesh withan average wire (or fiber) diameter in the range from about one micronto about 400 microns, and an average open area between wires (or fibers)in the range from about 60% to about 95%.

Catalyst layer 4330 is generally formed of a material that can catalyzea redox reaction in the charge carrier layer positioned below. Examplesof materials from which catalyst layer can be formed include platinumand polymers, such as polythiophenes, polypyrroles, polyanilines andtheir derivatives. Examples of polythiophene derivatives includepoly(3,4-ethylenedioxythiophene) (“PEDOT”), poly(3-butylthiophene),poly[3 (4-octylphenyl)thiophene], poly(thieno[3,4-b]thiophene)(“PT34bT”), andpoly(thieno[3,4-b]thiophene-co-3,4-ethylenedioxythiophene)(“PT34bT-PEDOT”). Examples of catalyst layers containing one or morepolymers are disclosed, for example, in co-pending and commonly ownedU.S. Ser. Nos. 10/897,268 and 60/637,844, both of which are herebyincorporated by reference.

Substrate 4310 can be formed from a mechanically-flexible material, suchas a flexible polymer, or a rigid material, such as a glass. Examples ofpolymers that can be used to form a flexible substrate includepolyethylene naphthalates (PEN), polyethylene terephthalates (PET),polyethyelenes, polypropylenes, polyamides, polymethylmethacrylate,polycarbonate, and/or polyurethanes. Flexible substrates can facilitatecontinuous manufacturing processes such as web-based coating andlamination. However, rigid substrate materials may also be used, such asdisclosed, for example, in co-pending and commonly owned U.S. Ser. No.10/351,265, which is hereby incorporated by reference.

The thickness of substrate 4310 can vary as desired. Typically,substrate thickness and type are selected to provide mechanical supportsufficient for the DSSC to withstand the rigors of manufacturing,deployment, and use. Substrate 4310 can have a thickness of from aboutsix microns to about 5,000 microns (e.g., from about 6 microns to about50 microns, from about 50 microns to about 5,000 microns, from about 100microns to about 1,000 microns).

In embodiments where electrically conductive layer 4320 is transparent,substrate 310 is formed from a transparent material. For example,substrate 4310 can be formed from a transparent glass or polymer, suchas a silica-based glass or a polymer, such as those listed above. Insuch embodiments, electrically conductive layer 4320 may also betransparent.

Substrate 4370 and electrically conductive layer 4360 can be asdescribed above regarding substrate 4310 and electrically conductivelayer 4320, respectively. For example, substrate 4370 can be formed fromthe same materials and can have the same thickness as substrate 4310. Insome embodiments however, it may be desirable for substrate 4370 to bedifferent from 4310 in one or more aspects. For example, where the DSSCis manufactured using a process that places different stresses on thedifferent substrates, it may be desirable for substrate 4370 to be moreor less mechanically robust than substrate 4310. Accordingly, substrate4370 may be formed from a different material, or may have a differentthickness that substrate 4310. Furthermore, in embodiments where onlyone substrate is exposed to an illumination source during use, it is notnecessary for both substrates and/or electrically conducting layers tobe transparent. Accordingly, one of substrates and/or correspondingelectrically conducting layer can be opaque.

Generally, charge carrier layer 4340 includes a material thatfacilitates the transfer of electrical charge from a ground potential ora current source to photoactive layer 4350. A general class of suitablecharge carrier materials include solvent-based liquid electrolytes,polyelectrolytes, polymeric electrolytes, solid electrolytes, n-type andp-type transporting materials (e.g., conducting polymers) and gelelectrolytes. Examples of gel electrolytes are disclosed, for example,in co-pending and commonly owned U.S. Ser. No. 10/350,912, which ishereby incorporated by reference. Other choices for charge carrier mediaare possible. For example, the charge carrier layer can include alithium salt that has the formula LiX, where X is an iodide, bromide,chloride, perchlorate, thiocyanate, trifluoromethyl sulfonate, orhexafluorophosphate.

The charge carrier media typically includes a redox system. Suitableredox systems may include organic and/or inorganic redox systems.Examples of such systems include cerium(III) sulphate/cerium(IV), sodiumbromide/bromine, lithium iodide/iodine, Fe²⁺/Fe³⁺, Co²⁺/Co³⁺, andviologens. Furthermore, an electrolyte solution may have the formulaM_(i)X_(j), where i and j are greater than or equal to one, where X isan anion, and M is lithium, copper, barium, zinc, nickel, a lanthanide,cobalt, calcium, aluminum, or magnesium. Suitable anions includechloride, perchlorate, thiocyanate, trifluoromethyl sulfonate, andhexafluorophosphate.

In some embodiments, the charge carrier media includes a polymericelectrolyte. For example, the polymeric electrolyte can includepoly(vinyl imidazolium halide) and lithium iodide and/or polyvinylpyridinium salts. In embodiments, the charge carrier media can include asolid electrolyte, such as lithium iodide, pyridimum iodide, and/orsubstituted imidazolium iodide.

The charge carrier media can include various types of polymericpolyelectrolytes. For example, suitable polyelectrolytes can includebetween about 5% and about 95% (e.g., 5-60%, 5-40%, or 5-20%) by weightof a polymer, e.g., an ion-conducting polymer, and about 5% to about 95%(e.g., about 35-95%, 60-95%, or 80-95%) by weight of a plasticizer,about 0.05 M to about 10 M of a redox electrolyte of organic orinorganic iodides (e.g., about 0.05-2 M, 0.05-1 M, or 0.05-0.5 M), andabout 0.01 M to about 1 M (e.g., about 0.05-0.5 M, 0.05-0.2 M, or0.05-0.1 M) of iodine. The ion-conducting polymer may include, forexample, polyethylene oxide (PEO), polyacrylonitrile (PAN),polymethylmethacrylate (PMMA), polyethers, and polyphenols. Examples ofsuitable plasticizers include ethyl carbonate, propylene carbonate,mixtures of carbonates, organic phosphates, butyrolactone, anddialkylphthalates.

In some embodiments, charge carrier layer 4340 can include one or morezwitterionic compounds. Charge carrier layers including one or morezwitterionic compounds are disclosed, for example, in co-pending andcommonly owned U.S. Ser. No. 11/000,276, which is hereby incorporated byreference.

FIG. 17 shows a process (a roll-to-roll process) 5000 for manufacturinga DSSC by advancing a substrate 5100 between rollers 5150. Substrate5100 can be advanced between rollers 5150 continuously, periodically, orirregularly during a manufacturing run.

An electrically conductive layer 5200 (e.g., a titanium foil) isattached to substrate 5100 adjacent location 5120.

An interconnected nanoparticle material is then formed on theelectrically conductive layer adjacent location 5130. The interconnectednanoparticle material can be formed by applying a solution containing alinking agent (e.g., polymeric linking agent, such as poly(n-butyltitanate)) and metal oxide nanoparticles (e.g., titania). In someembodiments, the polymeric linking agent and the metal oxidenanoparticles are separately applied to form the interconnectednanoparticle material. The polymeric linking agent and metal oxidenanoparticles can be heated (e.g., in an oven present in the system usedin the roll-to-roll process) to form the interconnected nanoparticlematerial.

One or more dyes are then applied (e.g., using silk screening, ink jetprinting, or gravure printing) to the interconnected nanoparticlematerial adjacent location 5350 to form a photoactive layer.

A charge carrier layer is deposited onto the patterned photoactive layeradjacent location 5160. The charge carrier layer can be deposited usingknown techniques, such as those noted above.

An electrically conductive layer 5600 (e.g., ITO) is attached tosubstrate 5700 adjacent location 5190.

A catalyst layer precursor is deposited on electrically conductive layer5600 adjacent location 5180. The catalyst layer precursor can bedeposited on electrically conductive layer 5600 using, for example,electrochemical deposition using chloroplatinic acid in anelectrochemical cell, or pyrolysis of a coating containing a platinumcompound (e.g., chloroplatinic acid). In general, the catalyst layerprecursor can be deposited using known coating techniques, such as spincoating, dip coating, knife coating, bar coating, spray coating, rollercoating, slot coating, gravure coating, screen coating, and/or ink jetprinting. The catalyst layer precursor is then heated (e.g., in an ovenpresent in the system used in the roll-to-roll process) to form thecatalyst layer. In some embodiments, electrically conductive material5600 can be at least partially coated with the catalyst layer beforeattaching to advancing substrate 5700. In certain embodiments, thecatalyst layer is applied directly to electrically conductive layer 5600(e.g., without the presence of a precursor).

In some embodiments, the method can include scoring the coating of afirst coated base material at a temperature sufficiently elevated topart the coating and melt at least a portion of the first base material,and/or scoring a coating of a second coated base material at atemperature sufficiently elevated to part the coating and at least aportion of the second base material, and optionally joining the firstand second base materials to form a photovoltaic module. DSSCs withmetal foil and methods for the manufacture are disclosed, for example,in co-pending and commonly owned U.S. Ser. No. 10/351,264, which ishereby incorporated by reference.

In certain embodiments, the method can include slitting (e.g.,ultrasonic slitting) to cut and/or seal edges of photovoltaic cellsand/or modules (e.g., to encapsulate the photoactive components in anenvironment substantially impervious to the atmosphere). Examples ofsuch methods are disclosed, for example, in co-pending and commonlyowned U.S. Ser. No. 10/351,250, which is hereby incorporated byreference.

Polymer Photovoltaic Cells

In certain embodiments, a photovoltaic cell is a polymer photovoltaiccell. FIG. 18 shows a polymer photovoltaic cell 6600 that includessubstrates 6610 and 6670, electrically conductive layers 6620 and 6660,a hole blocking layer 6630, a photoactive layer 6640, and a hole carrierlayer 6650.

In general, substrate 6610 and/or substrate 6670 can be as describedabove with respect to the substrates in a DSSC. Exemplary materialsinclude polyethylene tereplithalate (PET), polyethylene naphthalate(PEN), or a polyimide. An example of a polyimide is a KAPTON® polyimidefilm (available from E. I. du Pont de Nemours and Co.).

Generally, electrically conductive layer 6620 and/or electricallyconductive layer 670 can be as described with respect to theelectrically conductive layers in a DSSC.

Hole blocking layer 6630 is generally formed of a material that, at thethickness used in photovoltaic cell 6600, transports electrons toelectrically conductive layer 6620 and substantially blocks thetransport of holes to electrically conductive layer 6620. Examples ofmaterials from which layer 6630 can be formed include LiF, metal oxides(e.g., zinc oxide, titanium oxide) and combinations thereof. While thethickness of layer 630 can generally be varied as desired, thisthickness is typically at least 0.02 micron (e.g., at least about 0.03micron, at least about 0.04 micron, at least about 0.05 micron) thickand/or at most about 0.5 micron (e.g., at most about 0.4 micron, at mostabout 0.3 micron, at most about 0.2 micron, at most about 0.1 micron)thick. In some embodiments, this distance is from 0.01 micron to about0.5 micron. In some embodiments, layer 6630 is a thin LiF layer. Suchlayers are disclosed, for example, in co-pending and commonly owned U.S.Ser. No. 10/258,708, which is hereby incorporated by reference.

Hole carrier layer 6650 is generally formed of a material that, at thethickness used in photovoltaic cell 6600, transports holes toelectrically conductive layer 6660 and substantially blocks thetransport of electrons to electrically conductive layer 6660. Examplesof materials from which layer 6650 can be formed include polythiophenes(e.g., PEDOT), polyanilines, polyvinylcarbazoles, polyphenylenes,polyphenylvinylenes, polysilanes, polythienylenevinylenes,polyisothianaphthanenes and combinations thereof. While the thickness oflayer 6650 can generally be varied as desired, this thickness istypically at least 0.01 micron (e.g., at least about 0.05 micron, atleast about 0.1 micron, at least about 0.2 micron, at least about 0.3micron, at least about 0.5 micron) and/or at most about five microns(e.g., at most about three microns, at most about two microns, at mostabout one micron). In some embodiments, this distance is from 0.01micron to about 0.5 micron.

Photoactive layer 6640 generally includes an electron acceptor materialand an electron donor material.

Examples of electron acceptor materials include formed of fullerenes,oxadiazoles, carbon nanorods, discotic liquid crystals, inorganicnanoparticles (e.g., nanoparticles formed of zinc oxide, tungsten oxide,indium phosphide, cadmium selenide and/or lead sulphide), inorganicnanorods (e.g., nanorods formed of zinc oxide, tungsten oxide, indiumphosphide, cadmium selenide and/or lead sulphide), or polymerscontaining moieties capable of accepting electrons or forming stableanions (e.g., polymers containing CN groups, polymers containing CF₃groups). In some embodiments, the electron acceptor material is asubstituted fullerene (e.g., PCBM). In some embodiments, the fullerenescan be derivatized. For example, a fullerene derivative can includes afullerene (e.g., PCBG), a pendant group (e.g., a cyclic ether such asepoxy, oxetane, or furan) and a linking group that spaces the pendantgroup apart from the fullerene. The pendant group is generallysufficiently reactive that fullerene derivative may be reacted withanother compound (e.g., another fullerene derivative) to prepare areaction product. Photoactive layers including derivatized fullerenesare disclosed, for example, in co-pending and commonly owned U.S. Ser.No. 60/576,033, which is hereby incorporated by reference. Combinationsof electron acceptor materials can be used.

Examples of electron donor materials include discotic liquid crystals,polythiophenes, polyphenylenes, polyphenylvinylenes, polysilanes,polythienylvinylenes, and polyisothianaphthalenes. In some embodiments,the electron donor material is poly(3-hexylthiophene). In certainembodiments, photoactive layer 6640 can include a combination ofelectron donor materials.

In some embodiments, photoactive layer 6640 includes an orientedelectron donor material (e.g., a liquid crystal (LC) material), anelectroactive polymeric binder carrier (e.g., a poly(3-hexylthiophene)(P3HT) material), and a plurality of nanocrystals (e.g., orientednanorods including at least one of ZnO, WO₃, or TiO₂). The liquidcrystal (LC) material can be, for example, a discotic nematic LCmaterial, including a plurality of discotic mesogen units. Each unit caninclude a central group and a plurality of electroactive arms. Thecentral group can include at least one aromatic ring (e.g., ananthracene group). Each electroactive arm can include a plurality ofthiophene moieties and a plurality of alkyl moities. Within thephotoactive layer, the units can align in layers and columns.Electroactive arms of units in adjacent columns can interdigitate withone another facilitating electron transfer between units. Also, theelectroactive polymeric carrier can be distributed amongst the LCmaterial to further facilitate electron transfer. The surface of eachnanocrystal can include a plurality of electroactive surfactant groupsto facilitate electron transfer from the LC material and polymericcarrier to the nanocrystals. Each surfactant group can include aplurality of thiophene groups. Each surfactant can be bound to thenanocrystal via, for example, a phosphonic end-group. Each surfactantgroup also can include a plurality of alkyl moieties to enhancesolubility of the nanocrystals in the photoactive layer. Examples ofphotovoltaic cells are disclosed, for example, in co-pending andcommonly owned U.S. Ser. No. 60/664,336, which is hereby incorporated byreference.

In certain embodiments, the electron donor and electron acceptormaterials in layer 6640 can be selected so that the electron donormaterial, the electron acceptor material and their mixed phases have anaverage largest grain size of less than 500 nanometers in at least somesections of layer 6640. In such embodiments, preparation of layer 6640can include using a dispersion agent (e.g., chlorobenzene) as a solventfor both the electron donor and the electron acceptor. Such photoactivelayers are disclosed, for example, in co-pending and commonly owned U.S.Ser. No. 10/258,713, which is hereby incorporated by reference.

Generally, photoactive layer 6640 is sufficiently thick to be relativelyefficient at absorbing photons impinging thereon to form correspondingelectrons and holes, and sufficiently thin to be relatively efficient attransporting the holes and electrons to the electrically conductivelayers of the device. In certain embodiments, layer 6640 is at least0.05 micron (e.g., at least about 0.1 micron, at least about 0.2 micron,at least about 0.3 micron) thick and/or at most about one micron (e.g.,at most about 0.5 micron, at most about 0.4 micron) thick. In someembodiments, layer 6640 is from 0.1 micron to about 0.2 micron thick.

In some embodiments, the transparency of photoactive layer 6640 canchange as an electric field to which layer 6640 is exposed changes. Suchphotovoltaic cells are disclosed, for example, in co-pending andcommonly owned U.S. Ser. No. 10/486,116, which is hereby incorporated byreference.

In some embodiments, cell 6600 can further include an additional layer(e.g., formed of a conjugated polymer, such as a dopedpoly(3-alkylthiophene)) between photoactive layer 6640 and electricallyconductive layer 6620, and/or an additional layer (e.g., formed of aconjugated polymer) between photoactive layer 6640 and electricallyconductive layer 6660. The additional layer(s) can have a band gap(e.g., achieved by appropriate doping) of 1.8 eV. Such photovoltaiccells are disclosed, for example, in U.S. Pat. No. 6,812,399, which ishereby incorporated by reference.

Optionally, cell 6600 can further include a thin LiF layer betweenphotoactive layer 6640 and electrically conductive layer 6660. Suchlayers are disclosed, for example, in co-pending and commonly owned U.S.Ser. No. 10/258,708, which is hereby incorporated by reference.

In some embodiments, cell 6600 can be prepared as follows. Electricallyconductive layer 6620 is formed upon substrate 6610 using conventionaltechniques. Electrically conductive layer 6620 is configured to allow anelectrical connection to be made with an external load. Layer 6630 isformed upon electrically conductive layer 6620 using, for example, asolution coating process, such as slot coating, spin coating or gravurecoating. Photoactive layer 6640 is formed upon layer 6630 using, forexample, a solution coating process. Layer 6650 is formed on photoactivelayer 6640 using, for example, a solution coating process, such as slotcoating, spin coating or gravure coating. Electrically conductive layer6620 is formed upon layer 6650 using, for example, a vacuum coatingprocess, such as evaporation or sputtering.

In certain embodiments, preparation of cell 6600 can include a heattreatment above the glass transition temperature of the electron donormaterial for a predetermined treatment time. To increase efficiency, theheat treatment of the photovoltaic cell can be carried out for at leasta portion of the treatment time under the influence of an electric fieldinduced by a field voltage applied to the electrically conductive layersof the photovoltaic cell and exceeding the no-load voltage thereof. Suchmethods are disclosed, for example, in co-pending and commonly ownedU.S. Ser. No. 10/509,935, which is hereby incorporated by reference.

OTHER EMBODIMENTS

While certain embodiments have been disclosed, others are also possible.

As an example, although embodiments have been described in which anelectrically conductive interconnect is a stitch, in certain embodimentsan electrically conductive interconnect can be in the form of a stapleor a grommet. Examples of suitable material used to form the staplesand/or grommets include those noted above with respect to a stapleconductive interconnect.

As another example, although embodiments have been described in whichthe overlapping region between adjacent photovoltaic cells is securedwith one electrically conductive interconnect, in certain embodiments,in some embodiments more than one (e.g., two or more, three or more,four or more, five or more, six or more, seven or more) electricallyconductive interconnects can be used to secure the overlapping region.

As a further example, while embodiments have been described in which thecathode has a shaped or bent portion that forms an electrical connectionwith the anode, in some embodiments, the anode has a bent or shapedportion that forms an electrical connection with the cathode. In certainembodiments, both the cathodes and anodes have such bent or shapedportions.

As an additional example, in some embodiments, an electricallyconductive material, such as an electrically conductive adhesive, can bedisposed between the shaped or bent portion of the cathode and theanode.

As a further example, while photovoltaic modules have been described asincluding three photovoltaic cells, a photovoltaic module can includemore than three (e.g., four, five, six, seven) photovoltaic cells.

As another example, the adhesive can generally be formed of anyelectrically insulative adhesive. Examples of such adhesives includeco-polymers of olefins, acrylates, and urethanes, and other hotmeltadhesives. Examples of commercially available adhesives include Bynel®adhesives (available from DuPont), thermobond adhesive 845 (availablefrom 3M) and Dyneon™ THV220 fluoropolymer adhesive (available from 3M).

As an additional example, although the materials in the charge carrierlayers have been described above as being distinct from the materialsforming the photoactive layer, in some embodiments, one or morematerials within the charge carrier layer can be at least partiallydisposed within (e.g., intermixed with) the photoactive layer. Incertain embodiments, the materials within the charge carrier layer andthe photoactive layer can be combined to form a composite layer.

As a further example, a protective layer can be applied to the upperand/or lower substrates. A protective layer can be used to, for example,keep contaminants (e.g., dirt, water, oxygen, chemicals) out of aphotovoltaic cell and/or to mechanically strengthen the cell. Aprotective layer can be formed of a polymer (e.g., a fluorinatedpolymer).

As an additional example, although the materials in the charge carrierlayers have been described above as being distinct from the materialsforming the photoactive layer, in some embodiments, one or morematerials within the charge carrier layer can be at least partiallydisposed within (e.g., intermixed with) the photoactive layer. Incertain embodiments, the materials within the charge carrier layer andthe photoactive layer can be combined to form a composite layer.

As a further example, a protective layer can be applied to the upperand/or lower substrates. A protective layer can be used to, for example,keep contaminants (e.g., dirt, water, oxygen, chemicals) out of aphotovoltaic cell and/or to mechanically strengthen the cell. Aprotective layer can be formed of a polymer (e.g., a fluorinatedpolymer).

An another example, while embodiments have been described in which oneor more electrically conductive interconnects are used, in someembodiments, one or more interconnects that are not electricallyconductive can be used. In certain embodiments, only interconnects(e.g., one or more interconnects, two or more interconnects, three ormore interconnects, four or more interconnects, five or moreinterconnects, six or more interconnects) that are not electricallyconductive are used. In some embodiments, one or more electricallyconductive interconnects and one or more interconnects that are notelectrically conductive are used.

Further, while certain types of photovoltaic modules with interconnectshave been described, interconnects can also be used in other types ofmodules. Examples include photovoltaic modules that include photovoltaiccells with active material formed of amorphous silicon, cadmiumselenide, cadmium telluride, copper indium sulfide, and/or copper indiumgallium arsenide.

A photovoltaic module can generally be used as a component in anydesired application. FIG. 19 shows a photovoltaic module incorporatedinto exterior wall panels or exterior cladding fitted to a corrugatedstructure. FIG. 20 shows a photovoltaic module incorporated into anawning. FIG. 21 shows a photovoltaic module incorporated into a batterycharger a portable electronic device. Other applications include, forexample, package labeling, sensors, window shades, window blinds, and/orwindows (e.g., opaque windows, semitransparent windows).

The following example is illustrative and not intended to be limiting.

EXAMPLE 1

A photovoltaic cell was prepared as follows.

A 50 micron thick titanium foil was cut to have a size of 0.7 cm by 7 cmto form the cathode of the photovoltaic cell. A 15 micron thick porouslayer of TiO₂ was deposited on one of the surfaces of the cathode usingslot coating to form a portion of the photoactive layer. The TiO₂ layerwas coated with 30-50 mgs/m² of a photosensitizing agent to complete thephotoactive layer.

The photoactive layer was then imbibed with 0.3-1.0 g/m² of anelectrolyte that contains the redox couple I⁻/I₃ ⁻ to form the chargecarrier layer within the photovoltaic cell.

The anode of the photovoltaic cell was prepared by sputtering a 300 nmthick layer of ITO onto a surface of a PEN substrate that was 8 cm long,2 cm wide, and 200 microns thick. A less than one nm thick layer ofplatinum was then sputtered on top of the ITO layer to form the catalystlayer. The photovoltaic cell was completed by joining the catalyst layerto the photoactive layer imbibed with electrolyte using THV adhesive(available from Dyneon).

Another photovoltaic cell was prepared using the same process.

Each of the two photovoltaic cells was exposed to an A.M. 1.5 (100 mWper square cm) light source (Oriel Solar Simulator) for 30 seconds. Thecurrent generated within each of the two photovoltaic cells was measuredand plotted against voltage, the results of which are shown in FIG. 22.The efficiency of the first cell was 4.57%, and the efficiency of thesecond cell was 4.62%.

The fill factor of the first cell was 60.4%, and the fill factor of thesecond cell was 58.9%.

The two photovoltaic cells were then combined to create a photovoltaicmodule having the design shown in FIG. 4 (2 mm wide overlapping region).Steel staples (spaced approximately 5 mm from each other) were driventhrough the overlapping region to electrically connect and secure thetwo photovoltaic cells together to form a module.

The module was exposed to the same light source noted above and underthe same conditions for 30 seconds. The current generated within themodule was measured and plotted against voltage. The current versusvoltage results are shown in FIG. 22.

The efficiency of the module was 4.67% was determined as describedabove. The fill factor of the module was 58.7%.

Thus, the fill factor of the module was only slightly higher than thefill factor of either cell, and the efficiency of the module was onlyslightly lower than the individual efficiency of either cell.

Other embodiments are in the claims.

1. A module, comprising: a first photovoltaic cell comprising anelectrode with a first surface, a second surface opposite the firstsurface, and a third surface that connects the first and secondsurfaces, the first, second and third surfaces defining an end of theelectrode of the first photovoltaic cell; a second photovoltaic cellcomprising an electrode with a surface; and a conductive tape thatconnects the first and second photovoltaic cells, the conductive tapebeing in direct contact with the first, second and third surfaces of theelectrode of the first photovoltaic cell, and the conductive tape beingsupported by the surface of the electrode of the second photovoltaiccell, wherein the conductive tape is not disposed in the electrode ofthe first photovoltaic cell, the conductive tape is wrapped around theend of the electrode of the first photovoltaic cell so that a portion ofthe electrode of the first photovoltaic cell is disposed between thefirst and second surfaces of the electrode of the first photovoltaiccell.
 2. The module of claim 1, wherein the conductive tape is disposedon the first surface of the electrode of the first photovoltaic cell. 3.The module of claim 2, wherein the conductive tape is disposed on thesecond surface of the electrode of the first photovoltaic cell.
 4. Themodule of claim 1, wherein the conductive tape electrically connects thefirst and second photovoltaic cells.
 5. The module of claim 1, whereinthe conductive tape mechanically connects the first and secondphotovoltaic cells.
 6. The module of claim 1, wherein the firstphotovoltaic cell comprises a first polymer and a first fullerene. 7.The module of claim 6, wherein the second photovoltaic cell comprises asecond polymer and a second fullerene.
 8. The module of claim 7, whereinthe first and second polymers are the same.
 9. The module of claim 8,wherein the first and second fullerenes are the same.
 10. The module ofclaim 7, wherein the first and second fullerenes are the same.
 11. Themodule of claim 3, wherein the conductive tape is disposed on thesurface of the electrode of the second photovoltaic cell.
 12. The moduleof claim 1, wherein the conductive tape is not disposed in the electrodeof the second photovoltaic cell.